Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 | 2x 2x 2x 137x 137x 137x 137x 137x 137x 137x 137x 137x 137x 2218x 2218x 2218x 2x 6309x 6309x 6309x 2606x 2606x 2606x 7818x 27x 7791x 7818x 7818x 2606x 2606x 3703x 5755x 3701x 3701x 11103x 11103x 11103x 11103x 11103x 3701x 3701x 2x 2x 2x 377x 377x 377x 377x 153670x 153670x 153670x 2x 2x 2x 2x 1279x 1279x 1279x 1279x 2x 100x 100x 100x 100x 1179x 100x 100x 100x 100x 100x 100x 100x 100x 100x 100x 100x 1179x 1179x 1179x 100x 100x 100x 100x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 76x 2x 14x 14x 14x 14x 2x 64957x 64957x 64957x 64957x 64957x 2x 83543x 83543x 2x 4795x 4795x 4795x 107x 107x 107x 4795x 4795x 2x 3724x 3724x 3724x 2x 970x 970x 970x 970x 970x 970x 970x 970x 970x 970x 970x 970x 2x 2591x 2591x 2591x 2591x 2x 3271x 3271x 3271x 3271x 2x 75x 75x 75x 2x 2067x 2067x 2067x 2067x 2067x 2067x 2067x 2067x 2067x 2067x 2067x 2067x 2067x 2067x 2067x 2067x 2067x 2x 4633x 4633x 2x 3657x 3656x 3656x 3657x 100x 100x 100x 100x 100x 100x 100x 100x 100x 100x 100x 100x 100x 100x 100x 100x 100x 3556x 3556x 3657x 3657x 2x 964x 960x 960x 960x 960x 964x 2x 76x 76x 76x 76x 1350x 1250x 1250x 1350x 100x 100x 1350x 76x 76x 946x 946x 76x 76x 566x 566x 76x 76x 1119x 1119x 76x 76x 125x 125x 76x 76x 118x 118x 76x 76x 118x 118x 76x 76x 171x 171x 76x 76x 282x 282x 76x 237x 237x 237x 76x 239x 239x 237x 237x 239x 76x 2577x 2577x 76x 1688x 1687x 1687x 1688x 76x 2704x 2704x 76x 45467x 45467x 1x 1x 1x 45466x 45466x 45467x 76x 21x 21x 21x 21x 21x 76x 73x 73x 73x 73x 73x 73x 73x 73x 73x 73x 73x 73x 73x 73x 73x 73x 76x 2x 2x 2x 2x 4x 2x 2x 2x 76x 566x 566x 566x 566x 566x 566x 566x 566x 566x 566x 565x 1x 566x 566x 566x 566x 566x 2827x 2827x 2827x 566x 566x 566x 2261x 2261x 2261x 2261x 2261x 2261x 2261x 2261x 2261x 566x 566x 76x 1615x 1615x 76x 100x 76x 960x 960x 76x 498x 498x 76x 76x 18x 17x 18x 18x 76x 2042x 2042x 76x 76x 76x 183x 150x 150x 33x 33x 183x 76x 2x 2x 76x 76x 135x 135x 76x 20x 20x 76x 76x 4x 4x 76x 2x 2x 76x 3x 3x 76x 1x 1x 76x 3x 3x 76x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 76x 76x 76x 2x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 2x 178x 178x 178x 178x 178x 100x 78x 49x 29x 178x 178x 153x 25x 25x 2x 23x 178x 178x 178x 178x 178x 168x 178x 178x 178x 178x 178x 178x 178x 178x 178x 178x 2x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 903x 903x 903x 903x 75x 526x 526x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 75x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 75x 75x 75x 75x 75x 75x 75x 75x 75x 2x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1x 1600x 1600x 1600x 1600x 1x 1x 75x 75x 75x 75x 75x 75x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 315x 315x 2671x 2671x 2671x 2640x 18x 14x 8x 5x 2x 2671x 315x 315x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x 2x | /**
* A PDF page that accepts canvas drawing calls.
*
* The export already produced a PDF, and what was in it was one enormous
* picture of pixels. For a contact map that is honest — a matrix *is* a raster,
* and 12,000 chromosome bins are not paths. For a genome browser it is not:
* every mark in that view is a rectangle, a polyline or a word, and handing a
* journal a 300 dpi photograph of them means a figure nobody can restyle,
* recolour or scale, in a file fifty times the size of the drawing it contains.
*
* So this is the same drawing, written down as drawing. It implements the slice
* of `CanvasRenderingContext2D` the track renderers use — the list is short and
* fixed, and `render/tracks.ts`, `render/features.ts`, `render/lane.ts` and
* `render/browser.ts` are the only callers — and emits PDF content-stream
* operators instead of pixels. Nothing in those modules knows: they are handed a
* context and draw into it, which is the whole reason this is possible at all.
*
* Two deliberate limits, both stated rather than hidden:
*
* - **Text is Helvetica**, one of the fourteen fonts every PDF reader has, so
* nothing is embedded and the file stays small. Positions are computed from
* the *screen* font's metrics, because that is what the layout decisions above
* were made with, so a word may sit a shade narrower than its measured box.
* - **Transforms are baked into the coordinates** rather than emitted as `cm`.
* Every transform this app uses is a translate, a uniform scale or a quarter
* turn, so a point can be transformed in JavaScript and written down in page
* space — which keeps the clip stack and the line widths simple enough to be
* obviously right.
*/
import { deflateBytes, pointsForCssPixels } from './export'
import { PRODUCER } from '../version'
/** The 2×3 affine every canvas context carries, in canvas convention. */
interface Matrix {
a: number
b: number
c: number
d: number
e: number
f: number
}
const IDENTITY: Matrix = { a: 1, b: 0, c: 0, d: 1, e: 0, f: 0 }
function multiply(m: Matrix, n: Matrix): Matrix {
return {
a: m.a * n.a + m.c * n.b,
b: m.b * n.a + m.d * n.b,
c: m.a * n.c + m.c * n.d,
d: m.b * n.c + m.d * n.d,
e: m.a * n.e + m.c * n.f + m.e,
f: m.b * n.e + m.d * n.f + m.f,
}
}
/** The uniform scale a matrix applies, for line widths and font sizes. */
function scaleOf(m: Matrix): number {
return Math.sqrt(Math.abs(m.a * m.d - m.b * m.c)) || 1
}
interface State {
matrix: Matrix
fillStyle: string
/** The gradient a `fill` paints with, or `null` for the flat `fillStyle`. */
fillGradient: PageGradient | null
strokeStyle: string
lineWidth: number
globalAlpha: number
font: string
textAlign: CanvasTextAlign
textBaseline: CanvasTextBaseline
lineJoin: CanvasLineJoin
lineCap: CanvasLineCap
/** The dash pattern, in CSS pixels; empty is a solid line. */
lineDash: number[]
/**
* Whether a raster is smoothed where it is drawn larger than it is, and how
* well: drawing state on a canvas, so saved and restored with the rest.
* `true` and `'high'` together are what an image placed after them asks a
* viewer to interpolate (see `image`).
*/
imageSmoothingEnabled: boolean
imageSmoothingQuality: ImageSmoothingQuality
}
/**
* A CSS colour as PDF's `r g b` in `[0, 1]`.
*
* Hex and `rgb()`/`rgba()` only, which is everything this app produces: the
* palettes are hex literals and `getComputedStyle` normalises custom properties
* to one of the two. Anything else comes out black, which is a visible wrong
* answer rather than a silent one.
*/
export function pdfColour(css: string): [number, number, number] {
const value = css.trim()
const hex = /^#([0-9a-f]{3,8})$/i.exec(value)
if (hex !== null) {
const digits = hex[1]
const short = digits.length === 3 || digits.length === 4
const part = (index: number): number => {
const text = short
? digits[index].repeat(2)
: digits.slice(index * 2, index * 2 + 2)
return parseInt(text, 16) / 255
}
return [part(0), part(1), part(2)]
}
const rgb = /^rgba?\(([^)]+)\)$/i.exec(value)
if (rgb !== null) {
const parts = rgb[1].split(/[,/\s]+/).filter((piece) => piece !== '')
const channel = (index: number): number => {
const raw = parts[index] ?? '0'
const number = Number.parseFloat(raw)
if (!Number.isFinite(number)) return 0
return raw.endsWith('%') ? number / 100 : number / 255
}
return [channel(0), channel(1), channel(2)]
}
return [0, 0, 0]
}
/** Size in CSS pixels and whether it is bold, out of a CSS `font` shorthand. */
export function parseFont(font: string): { size: number; bold: boolean } {
const size = /(\d*\.?\d+)px/.exec(font)
const weight = /(^|\s)(bold|[6-9]00)(\s|$)/i.test(font)
return { size: size === null ? 10 : Number(size[1]), bold: weight }
}
function round(value: number): string {
return Number.isFinite(value) ? value.toFixed(3).replace(/\.?0+$/, '') : '0'
}
/**
* The subset of a 2D context the track renderers touch.
*
* Enumerated by reading every `ctx.` in `render/features.ts`, `render/tracks.ts`,
* `render/lane.ts` and `render/browser.ts`. It is deliberately not a full
* implementation and never will be: the day a renderer reaches for something
* outside this list, the export should fail loudly at the type level rather than
* silently drop a mark from the figure.
*/
export type VectorTarget = Pick<
CanvasRenderingContext2D,
| 'save'
| 'restore'
| 'beginPath'
| 'closePath'
| 'moveTo'
| 'lineTo'
| 'rect'
| 'arc'
| 'quadraticCurveTo'
| 'bezierCurveTo'
| 'fill'
| 'stroke'
| 'clip'
| 'fillRect'
| 'fillText'
| 'strokeText'
| 'measureText'
| 'translate'
| 'rotate'
| 'transform'
| 'setTransform'
| 'clearRect'
| 'strokeRect'
| 'drawImage'
| 'imageSmoothingEnabled'
| 'imageSmoothingQuality'
| 'fillStyle'
| 'strokeStyle'
| 'lineWidth'
| 'globalAlpha'
| 'font'
| 'textAlign'
| 'textBaseline'
| 'lineJoin'
| 'lineCap'
| 'setLineDash'
| 'getLineDash'
| 'createRadialGradient'
>
/**
* A radial gradient on the page: two circles and the colours between them,
* in the canvas's own coordinates as they were when it was made.
*
* Written as a PDF **radial shading** (type 3), painted with `sh` inside the
* path it fills, so a lit bead is a smooth sphere at any zoom rather than a
* raster of one (`structure/painter.ts`). Colours only; a stop's alpha is
* ignored, as a shading has none — the fill's `globalAlpha` still applies.
*/
class PageGradient {
readonly stops: Array<{ offset: number; rgb: [number, number, number] }> = []
constructor(readonly coords: [number, number, number, number, number, number]) {}
addColorStop(offset: number, colour: string): void {
if (!Number.isFinite(offset)) return
this.stops.push({ offset: Math.max(0, Math.min(1, offset)), rgb: pdfColour(colour) })
this.stops.sort((a, b) => a.offset - b.offset)
}
}
/** A gradient's stops as a PDF function of one variable on `[0, 1]`. */
function shadingFunction(stops: PageGradient['stops']): string {
const colour = (rgb: [number, number, number]): string => rgb.map(round).join(' ')
const pieces = stops.length === 0 ? [{ offset: 0, rgb: [0, 0, 0] as [number, number, number] }] : stops
const ramp = (from: [number, number, number], to: [number, number, number]): string =>
`<< /FunctionType 2 /Domain [0 1] /C0 [${colour(from)}] /C1 [${colour(to)}] /N 1 >>`
if (pieces.length === 1) return ramp(pieces[0].rgb, pieces[0].rgb)
// A stitching function: one linear ramp between each pair of stops, the
// stops themselves the bounds. Stops before the first offset and after the
// last take the end colours, as a canvas does.
const ends = [
...(pieces[0].offset > 0 ? [{ offset: 0, rgb: pieces[0].rgb }] : []),
...pieces,
...(pieces[pieces.length - 1].offset < 1 ? [{ offset: 1, rgb: pieces[pieces.length - 1].rgb }] : []),
]
// Two stops at one offset would be a ramp of no width, which not every
// reader takes: the later is kept, so a hard step softens to a ramp.
for (let k = ends.length - 2; k >= 0; k--) if (ends[k].offset === ends[k + 1].offset) ends.splice(k, 1)
if (ends.length === 1) return ramp(ends[0].rgb, ends[0].rgb)
const functions: string[] = []
const bounds: number[] = []
for (let k = 0; k + 1 < ends.length; k++) {
if (k > 0) bounds.push(ends[k].offset)
functions.push(ramp(ends[k].rgb, ends[k + 1].rgb))
}
return (
`<< /FunctionType 3 /Domain [0 1] /Functions [${functions.join(' ')}] ` +
`/Bounds [${bounds.map(round).join(' ')}] /Encode [${functions.map(() => '0 1').join(' ')}] >>`
)
}
/**
* A page, and a context that draws onto it.
*
* Sized in CSS pixels, exactly as the canvas is; the conversion to points
* happens once, at the end, so every number the renderers produce means the same
* thing here as it does on screen.
*/
export class VectorPage {
/** Hand this to a renderer. It is the context, in every sense that matters. */
readonly ctx: CanvasRenderingContext2D
private readonly ops: string[] = []
private readonly stack: State[] = []
private state: State
/**
* The current path, as construction operators in page space.
*
* Kept until `beginPath` (or `setOrigin`, which starts a sub-drawing as a
* new canvas would), and written out again in front of every operator
* that paints it, because this is where the two models part: a canvas's
* `fill`, `stroke` and `clip` each *read* the current path and leave it as it
* was, while in PDF every painting operator — `f`, `S`, the `n` after a
* `W` — *ends* the path it paints. The path used to be written once and
* dropped, so a shape filled and then stroked printed its fill and a bare
* `S`: every exported box plot lost its outline, whiskers and median, the
* reader's arrowheads printed as white halos with nothing inside, and a bar
* track's outline and the 1D browser's chips lost their borders.
*
* Held in page space, because a canvas fixes a path's geometry as it is
* built: a point is placed by the transform current when it is *added*,
* while a stroke's width and dashes are scaled by the one current when it is
* *stroked*. So the strings are written out again unchanged, and `setStroke`
* works out the width at the paint. Nor is the path drawing state — a
* canvas's `restore` does not put one back, and nor does this page's.
*/
private path: string[] = []
/** The current point, in page space; `null` while the path has no subpath. */
private current: [number, number] | null = null
/** Where the current subpath began, which is where `closePath` leaves the point. */
private subpathStart: [number, number] | null = null
private readonly alphas = new Map<number, string>()
/** The radial shadings painted on this page, as `/Shn` resources, in order. */
private readonly shadings: string[] = []
/**
* The rasters placed on this page, in the order they were drawn.
*
* A contact matrix is the one thing in this app that is honestly a raster —
* twelve thousand bins are pixels, and writing them as a million rectangles
* would be a larger, slower file of the same picture. So a page can hold
* both: the matrix as an image, and every axis, label, tick, divider, lane and
* legend around it as paths and text. That hybrid is what a journal wants and
* what neither a pure raster nor a pure vector page can be.
*/
private readonly images: Array<{ width: number; height: number; rgb: Uint8Array; interpolate: boolean }> = []
private readonly ruler: CanvasRenderingContext2D | null
constructor(
private readonly width: number,
private readonly height: number,
) {
this.state = {
matrix: { ...IDENTITY },
fillStyle: '#000000',
fillGradient: null,
strokeStyle: '#000000',
lineWidth: 1,
globalAlpha: 1,
font: '10px sans-serif',
textAlign: 'start',
textBaseline: 'alphabetic',
lineJoin: 'miter',
lineCap: 'butt',
lineDash: [],
imageSmoothingEnabled: true,
imageSmoothingQuality: 'low',
}
// Measured against a real canvas, because the *layout* above this — which
// name fits, where a label is centred — was decided with the screen's font.
// Measuring with Helvetica instead would produce a figure laid out for a
// font the screen never used.
const canvas =
typeof document === 'undefined' ? null : document.createElement('canvas')
this.ruler = canvas?.getContext('2d') ?? null
this.ctx = this.surface() as unknown as CanvasRenderingContext2D
}
// -------------------------------------------------------------------------
// Geometry
// -------------------------------------------------------------------------
/**
* Where a sub-drawing is being placed, in page pixels.
*
* Canvas has no such thing, and it is the one concept this page needs that it
* does not borrow. The heatmap and its legend each draw *from the origin* and
* each call `setTransform` to do it, so composing them on one canvas means
* rendering to intermediate canvases and `drawImage`-ing those into place —
* which is exactly right for a raster and exactly wrong here, since it would
* turn every tick and label in the legend back into pixels. An offset the
* absolute transform is applied *inside* lets each of them be drawn where it
* belongs, as itself.
*/
private originX = 0
private originY = 0
/**
* Place everything drawn from now on at this offset, in CSS pixels.
*
* On an empty path, too, because a sub-drawing placed here is one that has
* a canvas of its own on screen, and a canvas starts with no path. The page
* keeps a path past a paint, as a canvas does, and `save` and `restore` do
* not hold it — so without this the path one deck cell left behind would be
* the next cell's, and painted there by a renderer that trusted its canvas
* to start empty.
*/
setOrigin(x: number, y: number): void {
this.originX = x
this.originY = y
this.emptyPath()
}
/** Canvas point → page point. PDF's y runs up the page; canvas's runs down. */
private point(x: number, y: number): [number, number] {
const m = this.state.matrix
const px = m.a * x + m.c * y + m.e + this.originX
const py = m.b * x + m.d * y + m.f + this.originY
return [px, this.height - py]
}
private emit(op: string): void {
this.ops.push(op)
}
/**
* `/GSn gs`, allocating an ExtGState the first time an alpha is seen.
*
* Opaque gets a state of its own rather than being skipped, because PDF's
* alpha is graphics state and survives until something replaces it: a lane
* drawn at 0.65 would otherwise tint every mark after it.
*/
private alpha(): void {
const value = Math.max(0, Math.min(1, this.state.globalAlpha))
let name = this.alphas.get(value)
if (name === undefined) {
name = `GS${this.alphas.size}`
this.alphas.set(value, name)
}
this.emit(`/${name} gs`)
}
private setFill(): void {
const [r, g, b] = pdfColour(this.state.fillStyle)
this.emit(`${round(r)} ${round(g)} ${round(b)} rg`)
}
private setStroke(): void {
const [r, g, b] = pdfColour(this.state.strokeStyle)
this.emit(`${round(r)} ${round(g)} ${round(b)} RG`)
this.emit(`${round(Math.max(0.05, this.state.lineWidth * scaleOf(this.state.matrix)))} w`)
this.emit(`${this.state.lineJoin === 'round' ? 1 : this.state.lineJoin === 'bevel' ? 2 : 0} j`)
// Caps matter once a chart library is drawing the lines: `zrender` ends a
// tick with a round cap and a dashed grid line with a butt one, and a page
// that ignored the attribute would print every short segment a half-width
// longer or shorter than the screen drew it.
this.emit(`${this.state.lineCap === 'round' ? 1 : this.state.lineCap === 'square' ? 2 : 0} J`)
// PDF's dash operator takes the same array the canvas does, scaled by the
// same matrix the width is: `[] 0 d` is solid, which is what an empty
// pattern means on a canvas too. Without this an exported figure drew the
// alignment lane's mate threads solid, and a pair became indistinguishable
// from a fragment in the one artefact that leaves the application.
const dash = this.state.lineDash
const scale = scaleOf(this.state.matrix)
this.emit(
dash.length === 0
? '[] 0 d'
: `[${dash.map((on) => round(Math.max(0.05, on * scale))).join(' ')}] 0 d`,
)
}
/** No subpath and no current point: what `beginPath` leaves, and a new canvas has. */
private emptyPath(): void {
this.path = []
this.current = null
this.subpathStart = null
}
/** Begin a subpath at a page-space point. */
private startSubpath(at: [number, number]): void {
this.path.push(`${round(at[0])} ${round(at[1])} m`)
this.current = at
this.subpathStart = at
}
/**
* The current point, after starting a subpath at `at` if there is none.
*
* What a canvas does for a line or a curve drawn on an empty path, and what
* PDF cannot: its `l` and `c` are errors with no current point to start from.
*/
private ensureSubpath(at: [number, number]): [number, number] {
if (this.current === null) this.startSubpath(at)
return this.current ?? at
}
/**
* A rectangle as a closed subpath of its own, in page space.
*
* Four corners rather than PDF's `re`, because `re` is axis-aligned in
* *page* space and the matrix here may be a quarter turn.
*/
private rectangle(
x: number,
y: number,
w: number,
h: number,
): { segments: string[]; first: [number, number] } {
const corners = [
this.point(x, y),
this.point(x + w, y),
this.point(x + w, y + h),
this.point(x, y + h),
]
const segments = corners.map(
([px, py], index) => `${round(px)} ${round(py)} ${index === 0 ? 'm' : 'l'}`,
)
segments.push('h')
return { segments, first: corners[0] }
}
/**
* A path's construction operators, in front of the operator that paints it.
*
* Written out at every paint and never consumed: the segments stay the
* current path until `beginPath` (see `path`). This is also why a `q`
* from `save` can never land inside a path object, where PDF forbids it —
* nothing of a path reaches the stream until the operator that ends it.
*/
private trace(segments: readonly string[]): void {
for (const segment of segments) this.emit(segment)
}
/**
* Fill a path — the current one, or the rectangle of a `fillRect` — with the
* fill style, flat or radial.
*
* An empty path paints nothing, as on a canvas. Written out regardless, it
* was a bare `f`, an operator out of place in a PDF, or a shading behind a
* clip with no path, which a reader that drops the clip spreads over the
* whole page.
*/
private fillPath(segments: readonly string[], evenOdd: boolean): void {
if (segments.length === 0) return
this.alpha()
const gradient = this.state.fillGradient
if (gradient !== null) {
// The path as a clip, the shading painted through it, and the clip gone
// again with the `Q`. The shading is placed by the transform current
// now, as a canvas places a gradient when it fills rather than when the
// path was built.
const [x0, y0, r0, x1, y1, r1] = gradient.coords
const scale = scaleOf(this.state.matrix)
const [ax, ay] = this.point(x0, y0)
const [bx, by] = this.point(x1, y1)
const name = `Sh${this.shadings.length}`
this.shadings.push(
`/${name} << /ShadingType 3 /ColorSpace /DeviceRGB ` +
`/Coords [${[ax, ay, r0 * scale, bx, by, r1 * scale].map(round).join(' ')}] ` +
`/Function ${shadingFunction(gradient.stops)} /Extend [true true] >>`,
)
this.emit('q')
this.trace(segments)
this.emit(evenOdd ? 'W* n' : 'W n')
this.emit(`/${name} sh`)
this.emit('Q')
return
}
this.setFill()
this.trace(segments)
this.emit(evenOdd ? 'f*' : 'f')
}
/** Stroke a path — the current one, or the rectangle of a `strokeRect`. */
private strokePath(segments: readonly string[]): void {
if (segments.length === 0) return
this.alpha()
this.setStroke()
this.trace(segments)
this.emit('S')
}
// -------------------------------------------------------------------------
// The context
// -------------------------------------------------------------------------
private surface(): VectorTarget {
const self = this
const target: VectorTarget = {
get fillStyle(): string {
return self.state.fillStyle
},
set fillStyle(value: string | CanvasGradient | CanvasPattern) {
if (typeof value === 'string') {
self.state.fillStyle = value
self.state.fillGradient = null
} else if (value instanceof PageGradient) {
self.state.fillGradient = value
}
},
get strokeStyle(): string {
return self.state.strokeStyle
},
set strokeStyle(value: string | CanvasGradient | CanvasPattern) {
if (typeof value === 'string') self.state.strokeStyle = value
},
get lineWidth(): number {
return self.state.lineWidth
},
set lineWidth(value: number) {
self.state.lineWidth = value
},
get globalAlpha(): number {
return self.state.globalAlpha
},
set globalAlpha(value: number) {
self.state.globalAlpha = value
},
get font(): string {
return self.state.font
},
set font(value: string) {
self.state.font = value
},
get textAlign(): CanvasTextAlign {
return self.state.textAlign
},
set textAlign(value: CanvasTextAlign) {
self.state.textAlign = value
},
get textBaseline(): CanvasTextBaseline {
return self.state.textBaseline
},
set textBaseline(value: CanvasTextBaseline) {
self.state.textBaseline = value
},
get lineJoin(): CanvasLineJoin {
return self.state.lineJoin
},
set lineJoin(value: CanvasLineJoin) {
self.state.lineJoin = value
},
get lineCap(): CanvasLineCap {
return self.state.lineCap
},
set lineCap(value: CanvasLineCap) {
self.state.lineCap = value
},
// The path is not saved with the state, on a canvas or here: a path
// built inside a `save` is still the current path after the `restore`.
save: () => {
self.stack.push({ ...self.state, matrix: { ...self.state.matrix } })
self.emit('q')
},
restore: () => {
// An unmatched `restore` is a no-op on a canvas and a corrupt stream in
// a PDF, so the `Q` is emitted only when there was a `q` to match it.
const previous = self.stack.pop()
if (previous === undefined) return
self.state = previous
self.emit('Q')
},
// What empties the path, with `setOrigin`. A paint never does (see `path`).
beginPath: () => {
self.emptyPath()
},
closePath: () => {
// A canvas ignores it on an empty path; PDF's `h` has no point to
// close from and is an error.
if (self.current === null) return
self.path.push('h')
// What comes next starts where this subpath did, on a canvas and after
// PDF's `h` alike — so a curve's handles are worked out from there.
self.current = self.subpathStart
},
moveTo: (x: number, y: number) => {
self.startSubpath(self.point(x, y))
},
lineTo: (x: number, y: number) => {
const to = self.point(x, y)
// On an empty path a line is a move, as a canvas has it.
if (self.current === null) {
self.startSubpath(to)
return
}
self.path.push(`${round(to[0])} ${round(to[1])} l`)
self.current = to
},
rect: (x: number, y: number, w: number, h: number) => {
const { segments, first } = self.rectangle(x, y, w, h)
self.path.push(...segments)
// Closed, and the canvas begins the next subpath at its first corner,
// which is where PDF's `h` leaves the point too.
self.current = first
self.subpathStart = first
},
/**
* A cubic, which PDF has natively — one operator, no conversion.
*
* Wanted because a chart library's SVG is cubics: every smoothed line,
* every rounded corner and every arc `zrender` emits arrives as `C`, and
* a page that could only take quadratics would have to approximate them
* (`figures/svgPaint.ts`).
*/
bezierCurveTo: (
c1x: number,
c1y: number,
c2x: number,
c2y: number,
x: number,
y: number,
) => {
const [ax, ay] = self.point(c1x, c1y)
// On an empty path a canvas starts the subpath at the first handle.
self.ensureSubpath([ax, ay])
const [bx, by] = self.point(c2x, c2y)
const end = self.point(x, y)
self.path.push(
`${round(ax)} ${round(ay)} ${round(bx)} ${round(by)} ${round(end[0])} ${round(end[1])} c`,
)
self.current = end
},
quadraticCurveTo: (cx: number, cy: number, x: number, y: number) => {
// PDF has only cubics, so the quadratic is raised a degree — exactly,
// which is what makes an arc in the figure the arc that was on screen.
// Worked in page space, from the point the path is actually at: each
// handle is two thirds of the way from its end to the control point,
// which an affine map preserves, so a start placed under an earlier
// transform is taken where it was put rather than re-placed.
const control = self.point(cx, cy)
const from = self.ensureSubpath(control)
const end = self.point(x, y)
const toward = (point: [number, number]): string =>
[0, 1].map((axis) => round(point[axis] + (2 / 3) * (control[axis] - point[axis]))).join(' ')
self.path.push(`${toward(from)} ${toward(end)} ${round(end[0])} ${round(end[1])} c`)
self.current = end
},
arc: (
x: number,
y: number,
radius: number,
start: number,
end: number,
counter?: boolean,
) => {
// As cubics, a quarter turn at most each — the standard approximation,
// within three parts in ten thousand of the radius. It used to be 24
// straight segments, which no one saw on a dot; a lit bead zoomed to
// the size of a coin is a polygon at that, and a page of paths is
// there to be zoomed.
const sweep = counter === true ? start - end : end - start
// A sweep of a whole turn or more is the whole circle, as the canvas
// defines it — and the modulo below reads exactly one turn as none, which
// drew every full circle in a figure as a path of zero length: a points
// lane's dots and a loop's ring were on screen and not in the PDF.
const span =
sweep >= Math.PI * 2
? Math.PI * 2
: ((sweep % (Math.PI * 2)) + Math.PI * 2) % (Math.PI * 2)
const direction = counter === true ? -1 : 1
const steps = Math.max(1, Math.ceil(span / (Math.PI / 2) - 1e-9))
const piece = (span / steps) * direction
// Each control point lies along the tangent at its end, this far.
const reach = (4 / 3) * Math.tan(piece / 4) * radius
const at = (angle: number): { x: number; y: number } => ({
x: x + Math.cos(angle) * radius,
y: y + Math.sin(angle) * radius,
})
let last = at(start)
// A subpath of its own from the arc's start. A canvas would join it to
// a current point with a line instead; every caller here begins an arc
// on an empty path or at that very point, where the two are one drawing.
self.startSubpath(self.point(last.x, last.y))
for (let i = 0; i < steps; i++) {
const from = start + piece * i
const to = from + piece
const end = at(to)
const c1 = self.point(last.x - Math.sin(from) * reach, last.y + Math.cos(from) * reach)
const c2 = self.point(end.x + Math.sin(to) * reach, end.y - Math.cos(to) * reach)
const [ex, ey] = self.point(end.x, end.y)
self.path.push(`${c1.map(round).join(' ')} ${c2.map(round).join(' ')} ${round(ex)} ${round(ey)} c`)
last = end
}
self.current = self.point(last.x, last.y)
},
// The fill rule, when one is passed. The page has no `Path2D`, so one
// passed in its place is not read, and the current path is filled.
fill: (rule?: unknown) => {
self.fillPath(self.path, rule === 'evenodd')
},
createRadialGradient: (x0: number, y0: number, r0: number, x1: number, y1: number, r1: number) =>
new PageGradient([x0, y0, r0, x1, y1, r1]) as unknown as CanvasGradient,
stroke: () => {
self.strokePath(self.path)
},
setLineDash: (pattern: Iterable<number>) => {
// Copied, and non-finite entries dropped: the canvas ignores a pattern
// containing one, and a `NaN` reaching the operator stream is a PDF no
// reader will open.
self.state.lineDash = [...pattern].filter((on) => Number.isFinite(on) && on >= 0)
},
getLineDash: () => [...self.state.lineDash],
clip: (rule?: unknown) => {
// The path stays the current path, as after a paint: a clip and then a
// fill fill the shape clipped to. An empty path clips everything away
// on a canvas, and PDF's `W` must have a path to read, so that is a
// rectangle of no size.
if (self.path.length === 0) self.emit('0 0 0 0 re')
else self.trace(self.path)
self.emit(rule === 'evenodd' ? 'W* n' : 'W n')
},
// A rectangle of its own, painted without touching the current path: a
// canvas's `fillRect` and `strokeRect` leave the path as they found it.
// Going through `beginPath` and `rect` threw away a path the caller had
// built and not yet painted, and left the rectangle in its place.
fillRect: (x: number, y: number, w: number, h: number) => {
self.fillPath(self.rectangle(x, y, w, h).segments, false)
},
fillText: (text: string, x: number, y: number) => self.text(text, x, y, false),
strokeText: (text: string, x: number, y: number) => self.text(text, x, y, true),
measureText: (text: string): TextMetrics => {
if (self.ruler === null) {
return { width: text.length * parseFont(self.state.font).size * 0.55 } as TextMetrics
}
self.ruler.font = self.state.font
return self.ruler.measureText(text)
},
translate: (x: number, y: number) => {
self.state.matrix = multiply(self.state.matrix, { a: 1, b: 0, c: 0, d: 1, e: x, f: y })
},
rotate: (angle: number) => {
const cos = Math.cos(angle)
const sin = Math.sin(angle)
self.state.matrix = multiply(self.state.matrix, {
a: cos,
b: sin,
c: -sin,
d: cos,
e: 0,
f: 0,
})
},
/**
* Multiply, rather than replace.
*
* The one canvas transform the painters above never needed, and the only
* one an SVG replay can use: a `<g transform>` composes with whatever the
* caller already put on the context, and `setTransform` — which throws
* the caller's own placement away — would strand the whole figure at the
* page origin (`figures/svgPaint.ts`).
*/
transform: ((a: number, b: number, c: number, d: number, e: number, f: number) => {
self.state.matrix = multiply(self.state.matrix, { a, b, c, d, e, f })
}) as CanvasRenderingContext2D['transform'],
setTransform: ((a: number, b: number, c: number, d: number, e: number, f: number) => {
self.state.matrix = { a, b, c, d, e, f }
}) as CanvasRenderingContext2D['setTransform'],
// A page starts empty and is drawn in order, so there is nothing to clear:
// whatever a caller is erasing has not been written yet. Accepted rather
// than omitted because the heatmap clears before it draws, and a missing
// member is a `TypeError` in the middle of an export.
clearRect: () => {},
strokeRect: (x: number, y: number, w: number, h: number) => {
self.strokePath(self.rectangle(x, y, w, h).segments)
},
// Nearest-neighbour or bilinear is a question about *pixels*, and the
// answer on paper is whatever the reader's viewer does with the image —
// except where a figure asks for smoothing at high quality, which is the
// one painter that wants its image read as a continuous picture (a
// list's heatmap, `analysisPlots.drawListImage`): that image carries
// `/Interpolate true`, and every other is left to the viewer as before.
set imageSmoothingEnabled(value: boolean) {
self.state.imageSmoothingEnabled = value
},
get imageSmoothingEnabled(): boolean {
return self.state.imageSmoothingEnabled
},
set imageSmoothingQuality(value: ImageSmoothingQuality) {
self.state.imageSmoothingQuality = value
},
get imageSmoothingQuality(): ImageSmoothingQuality {
return self.state.imageSmoothingQuality
},
drawImage: ((
source: CanvasImageSource,
a?: number,
b?: number,
c?: number,
d?: number,
e?: number,
f?: number,
g?: number,
h?: number,
) => {
self.image(source, [a, b, c, d, e, f, g, h])
}) as CanvasRenderingContext2D['drawImage'],
}
return target
}
/**
* Place a raster.
*
* The three call shapes canvas has, resolved to one: a source rectangle and a
* destination rectangle in the caller's own coordinates. The destination is
* then transformed like any other geometry, which is what lets a matrix drawn
* through a `setTransform` land in exactly the place the screen put it.
*
* Only axis-aligned placement is expressed, because that is the only kind this
* app performs on an image — a rotated matrix is not a thing the heatmap draws
* — and a `cm` for the general case would be a second coordinate story to keep
* true.
*/
private image(source: CanvasImageSource, args: Array<number | undefined>): void {
const natural = sizeOf(source)
if (natural === null) return
const [a, b, c, d, e, f, g, h] = args
let crop = { x: 0, y: 0, width: natural.width, height: natural.height }
let dest: { x: number; y: number; width: number; height: number }
if (typeof e === 'number' && typeof f === 'number') {
crop = { x: a ?? 0, y: b ?? 0, width: c ?? natural.width, height: d ?? natural.height }
dest = { x: e, y: f, width: g ?? crop.width, height: h ?? crop.height }
} else {
dest = { x: a ?? 0, y: b ?? 0, width: c ?? natural.width, height: d ?? natural.height }
}
const rgb = pixelsOf(source, crop)
if (rgb === null) return
// The corners through the matrix, then the axis-aligned box they span.
const first = this.point(dest.x, dest.y)
const last = this.point(dest.x + dest.width, dest.y + dest.height)
const x0 = Math.min(first[0], last[0])
const y0 = Math.min(first[1], last[1])
const width = Math.abs(last[0] - first[0])
const height = Math.abs(last[1] - first[1])
if (!(width > 0) || !(height > 0)) return
this.images.push({
width: crop.width,
height: crop.height,
rgb,
interpolate: this.state.imageSmoothingEnabled && this.state.imageSmoothingQuality === 'high',
})
const name = `Im${this.images.length - 1}`
this.alpha()
this.emit('q')
this.emit(`${round(width)} 0 0 ${round(height)} ${round(x0)} ${round(y0)} cm`)
this.emit(`/${name} Do`)
this.emit('Q')
}
/**
* One run of text.
*
* `textAlign` and `textBaseline` have no PDF equivalent, so they are resolved
* here into an offset — measured with the screen font, which is what the
* caller centred against.
*
* A stroked run is the *halo* `laneText` puts behind its labels so a name
* survives over the track's own ink, and it is kept rather than dropped: PDF's
* text render mode 1 strokes the glyph outlines exactly as the canvas does, so
* the figure reads the way the screen did. Rendering mode is text state and
* persists, hence the explicit `Tr` on both paths.
*/
private text(text: string, x: number, y: number, halo: boolean): void {
if (text === '') return
const { size, bold } = parseFont(this.state.font)
const width = this.ctx.measureText(text).width
const dx =
this.state.textAlign === 'center'
? -width / 2
: this.state.textAlign === 'right' || this.state.textAlign === 'end'
? -width
: 0
// Canvas baselines, as a shift of the alphabetic baseline. The numbers are
// the usual approximations of a font's metrics and are within a pixel for
// every size this app draws at.
const dy =
this.state.textBaseline === 'middle'
? size * 0.35
: this.state.textBaseline === 'top' || this.state.textBaseline === 'hanging'
? size * 0.8
: this.state.textBaseline === 'bottom'
? -size * 0.2
: 0
// `dx`/`dy` are in the *caller's* units, which is what `measureText` and the
// font size are both in: a canvas measures text before the transform and
// scales the result with everything else. `point` then applies the matrix to
// the whole thing, exactly as the canvas would.
const m = this.state.matrix
const factor = scaleOf(m)
const [px, py] = this.point(x + dx, y + dy)
this.alpha()
if (halo) this.setStroke()
else this.setFill()
this.emit('BT')
this.emit(`${halo ? 1 : 0} Tr`)
this.emit(`/${bold ? 'F2' : 'F1'} ${round(size * factor)} Tf`)
// The text matrix carries the rotation; the translation is already baked
// into the point above. `d` is negated because the page's y runs the other
// way from the canvas's.
this.emit(
`${round(m.a / factor)} ${round(-m.b / factor)} ${round(-m.c / factor)} ` +
`${round(m.d / factor)} ${round(px)} ${round(py)} Tm`,
)
this.emit(`(${escapeText(text)}) Tj`)
this.emit('ET')
}
/** The page as a one-page PDF. */
async toBlob(meta: { title?: string; created?: Date } = {}): Promise<Blob> {
const pageWidth = pointsForCssPixels(this.width)
const pageHeight = pointsForCssPixels(this.height)
const scale = pageWidth / this.width
// One `cm` for the whole stream: everything above is in CSS pixels measured
// from the top-left, and this is the single place that becomes points.
const body = `q ${round(scale)} 0 0 ${round(scale)} 0 ${round(pageHeight - this.height * scale)} cm\n${this.ops.join('\n')}\nQ\n`
// Compressed, because a whole-genome view of a GTF is a few hundred thousand
// path operators and they are almost entirely repeated digits — this is the
// difference between a 12 MB figure and a 700 kB one.
const { data: stream, filter } = await deflateBytes(new TextEncoder().encode(body))
const gs = [...this.alphas.entries()]
.map(([value, name]) => `/${name} << /Type /ExtGState /ca ${round(value)} /CA ${round(value)} >>`)
.join(' ')
// The rasters, deflated. Numbered from 8, after the seven fixed objects, so
// the page's `/XObject` dictionary can be written before any of them exists.
const packed = await Promise.all(this.images.map((image) => deflateBytes(image.rgb)))
const xobjects = this.images
.map((_image, index) => `/Im${index} ${8 + index} 0 R`)
.join(' ')
const chunks: Uint8Array[] = []
const offsets: number[] = []
let length = 0
const encoder = new TextEncoder()
const push = (part: Uint8Array | string): void => {
const bytes = typeof part === 'string' ? encoder.encode(part) : part
chunks.push(bytes)
length += bytes.length
}
const startObject = (): void => {
offsets.push(length)
}
push('%PDF-1.4\n%âãÏÓ\n')
startObject()
push('1 0 obj\n<< /Type /Catalog /Pages 2 0 R >>\nendobj\n')
startObject()
push('2 0 obj\n<< /Type /Pages /Kids [3 0 R] /Count 1 >>\nendobj\n')
startObject()
push(
`3 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 ${round(pageWidth)} ${round(pageHeight)}] ` +
'/Resources << /Font << /F1 5 0 R /F2 6 0 R >> ' +
`/ExtGState << ${gs} >>` +
`${this.shadings.length === 0 ? '' : ` /Shading << ${this.shadings.join(' ')} >>`}` +
`${xobjects === '' ? '' : ` /XObject << ${xobjects} >>`} >> /Contents 4 0 R >>\nendobj\n`,
)
startObject()
push(
`4 0 obj\n<< /Length ${stream.length}` +
`${filter === null ? '' : ` /Filter ${filter}`} >>\nstream\n`,
)
push(stream)
push('\nendstream\nendobj\n')
startObject()
push(
'5 0 obj\n<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica /Encoding /WinAnsiEncoding >>\nendobj\n',
)
startObject()
push(
'6 0 obj\n<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica-Bold /Encoding /WinAnsiEncoding >>\nendobj\n',
)
startObject()
const created = meta.created ?? new Date()
push(
`7 0 obj\n<< /Producer (${escapeText(PRODUCER)}) ` +
(meta.title === undefined ? '' : `/Title (${escapeText(meta.title)}) `) +
`/CreationDate (D:${pdfDate(created)}) >>\nendobj\n`,
)
for (const [index, image] of this.images.entries()) {
const { data, filter: imageFilter } = packed[index]
startObject()
push(
`${8 + index} 0 obj\n<< /Type /XObject /Subtype /Image ` +
`/Width ${image.width} /Height ${image.height} ` +
`/ColorSpace /DeviceRGB /BitsPerComponent 8 ` +
`${image.interpolate ? '/Interpolate true ' : ''}` +
`${imageFilter === null ? '' : `/Filter ${imageFilter} `}` +
`/Length ${data.length} >>\nstream\n`,
)
push(data)
push('\nendstream\nendobj\n')
}
const xref = length
let table = `xref\n0 ${offsets.length + 1}\n0000000000 65535 f \n`
for (const offset of offsets) table += `${String(offset).padStart(10, '0')} 00000 n \n`
push(table)
push(
`trailer\n<< /Size ${offsets.length + 1} /Root 1 0 R /Info 7 0 R >>\nstartxref\n${xref}\n%%EOF\n`,
)
return new Blob(chunks as BlobPart[], { type: 'application/pdf' })
}
}
/** The natural pixel size of anything canvas will draw, or `null`. */
function sizeOf(source: CanvasImageSource): { width: number; height: number } | null {
const value = source as { width?: unknown; height?: unknown }
const width = typeof value.width === 'number' ? value.width : 0
const height = typeof value.height === 'number' ? value.height : 0
return width > 0 && height > 0 ? { width, height } : null
}
/**
* A source's pixels as packed RGB, alpha composited onto white.
*
* PDF has no alpha channel on an image without a soft mask, and the page under
* this one is white, so compositing here is the same picture in one object
* instead of two. Read through a scratch canvas rather than from the source
* directly, because `drawImage` is the only thing that takes every shape of
* `CanvasImageSource` and turns it into pixels.
*/
function pixelsOf(
source: CanvasImageSource,
crop: { x: number; y: number; width: number; height: number },
): Uint8Array | null {
if (typeof document === 'undefined') return null
const scratch = document.createElement('canvas')
scratch.width = Math.max(1, Math.round(crop.width))
scratch.height = Math.max(1, Math.round(crop.height))
const ctx = scratch.getContext('2d', { willReadFrequently: true })
if (ctx === null) return null
ctx.fillStyle = '#ffffff'
ctx.fillRect(0, 0, scratch.width, scratch.height)
ctx.drawImage(
source,
crop.x,
crop.y,
crop.width,
crop.height,
0,
0,
scratch.width,
scratch.height,
)
const rgba = ctx.getImageData(0, 0, scratch.width, scratch.height).data
const rgb = new Uint8Array((rgba.length / 4) * 3)
for (let i = 0, o = 0; i < rgba.length; i += 4, o += 3) {
rgb[o] = rgba[i]
rgb[o + 1] = rgba[i + 1]
rgb[o + 2] = rgba[i + 2]
}
return rgb
}
/** `D:YYYYMMDDHHmmSS`, which is the only date format PDF has. */
function pdfDate(now: Date): string {
const pad = (n: number): string => String(n).padStart(2, '0')
return (
`${now.getUTCFullYear()}${pad(now.getUTCMonth() + 1)}${pad(now.getUTCDate())}` +
`${pad(now.getUTCHours())}${pad(now.getUTCMinutes())}${pad(now.getUTCSeconds())}Z`
)
}
/**
* The punctuation WinAnsi has and Latin-1 does not.
*
* `0x80`–`0x9f` is where CP1252 puts the typographic marks, and one of them is
* the en dash this app writes every range with — `0 – 130` under every track.
* Without the map that dash is the one character in the figure that comes out as
* a question mark.
*/
const WIN_ANSI = new Map<string, number>([
['€', 0x80],
['‚', 0x82],
['ƒ', 0x83],
['„', 0x84],
['…', 0x85],
['†', 0x86],
['‡', 0x87],
['ˆ', 0x88],
['‰', 0x89],
['Š', 0x8a],
['‹', 0x8b],
['Œ', 0x8c],
['Ž', 0x8e],
['‘', 0x91],
['’', 0x92],
['“', 0x93],
['”', 0x94],
['•', 0x95],
['–', 0x96],
['—', 0x97],
['˜', 0x98],
['™', 0x99],
['š', 0x9a],
['›', 0x9b],
['œ', 0x9c],
['ž', 0x9e],
['Ÿ', 0x9f],
])
/**
* A PDF literal string.
*
* Backslash, both parens, and anything outside WinAnsi — a contig called
* `chrI‑α` is legal and would otherwise close the string early or write a byte
* the reader maps to something else.
*/
export function escapeText(text: string): string {
let out = ''
for (const character of text) {
const code = character.codePointAt(0) ?? 0
const mapped = WIN_ANSI.get(character)
if (character === '\\' || character === '(' || character === ')') out += `\\${character}`
else if (code >= 32 && code <= 126) out += character
else if (mapped !== undefined) out += `\\${mapped.toString(8).padStart(3, '0')}`
// 0x80–0x9f are control characters in Latin-1 and typography in WinAnsi, so
// a raw one of those would be written as a glyph it is not.
else if (code >= 0xa0 && code <= 0xff) out += `\\${code.toString(8).padStart(3, '0')}`
else if (SPACE_LIKE.has(code)) out += '\\240'
else if (SPELLED.has(code)) out += escapeText(SPELLED.get(code) as string)
else out += '?'
}
return out
}
/**
* The spaces WinAnsi has no byte for, folded onto its non-breaking one.
*
* Not a nicety. `fmt.int` formats through `Intl.NumberFormat` in the *viewer's*
* locale, and half of Europe groups digits with a space rather than a comma —
* `fr-FR` picks U+202F NARROW NO-BREAK SPACE, others U+00A0. The first has no
* WinAnsi byte, so a figure exported in French came out reading `7?071 in view`:
* every grouped number in the figure corrupted, by the app's own formatter, in
* the one place a reader would never think to look for a locale bug.
*/
/**
* The symbols WinAnsi has no byte for, spelled out rather than dropped.
*
* `≤` is the one that matters: every colour bar this app draws ends with
* `≤ 0.000061` under its lowest stop, and in the exported figure that read
* `? 0.000061`. Two characters that say the same thing beat one that says
* nothing, and neither is a reason to embed a font.
*/
const SPELLED = new Map<number, string>([
[0x2264, '<='],
[0x2265, '>='],
[0x2260, '!='],
[0x2248, '~'],
[0x2212, '-'],
[0x2032, "'"],
[0x2033, '"'],
])
const SPACE_LIKE = new Set([
0x2007, // figure space
0x2008, // punctuation space
0x2009, // thin space
0x200a, // hair space
0x202f, // narrow no-break space
])
|